Enhanced Shrinkage of Lanthanum Strontium Manganite (La0.90Sr0.10MnO3+?) Resulting from Thermal and Oxygen Partial Pressure Cycling
| Autor: | Edwin C. Thomsen, Harlan U. Anderson, Larry R. Pederson, Prabhakar Singh, Xiao-Dong Zhou, Gregory W. Coffey, Benjamin P. McCarthy |
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| Rok vydání: | 2007 |
| Předmět: |
Materials science
Lanthanum strontium manganite Analytical chemistry Mineralogy chemistry.chemical_element Temperature cycling Partial pressure Atmospheric temperature range Oxygen chemistry.chemical_compound chemistry Orders of magnitude (specific energy) Vacancy defect Materials Chemistry Ceramics and Composites Shrinkage |
| Zdroj: | Journal of the American Ceramic Society. 90:3255-3262 |
| ISSN: | 1551-2916 0002-7820 |
| DOI: | 10.1111/j.1551-2916.2007.01890.x |
| Popis: | Exposure of (La0.90Sr0.10)0.98MnO3+δ (LSM-10) to repeated oxygen partial pressure cycles (air/10 ppm O2) resulted in enhanced densification rates, similar to behavior shown previously due to thermal cycling. Shrinkage rates in the temperature range 700°–1000°C were orders of magnitude higher than Makipirtti–Meng model estimations based on stepwise isothermal dilatometry results at a high temperature. A maximum in enhanced shrinkage due to oxygen partial pressure cycling occurred at 900°C. Shrinkage was the greatest when LSM-10 bars that were first equilibrated in air were exposed to gas flows of lower oxygen fugacity than in the reverse direction. The former creates transient cation and oxygen vacancies well above the equilibrium concentration, resulting in enhanced mobility. These vacancies annihilate as Schottky equilibria are reestablished, whereas the latter condition does not lead to excess vacancy concentrations. |
| Databáze: | OpenAIRE |
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